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Date: Wed, 17 Sep 2014 23:57:00 -0000
Message-ID: <CAH6eHdTv3DsVCtpB3nap=3LHUGCYFoQ1DuSvz_zuuxN=Fh_cpw@mail.gmail.com>
Subject: Re: Possible bug in gcc 4.4.7
From: Jonathan Wakely <jwakely.gcc@gmail.com>
To: "Andy Falanga (afalanga)" <afalanga@micron.com>
Cc: "gcc-help@gcc.gnu.org" <gcc-help@gcc.gnu.org>
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On 17 September 2014 18:15, Andy Falanga (afalanga) wrote:
>> That reinterpret_cast looks dodgy to me, accessing the object through a
>> different type is undefined behaviour. What's wrong with doing it
>> safely?
>>
>> Flag operator &=(Flag& f1, Flag f2) {
>>   unsigned int i = f1;
>>   i &= static_cast<unsigned int>(f2);
>>   return f1 = static_cast<Flag>(i);
>> }
>
> Ha, nothing except my thinking that, because I was casting a reference, I had to use reinterpret_cast<>.

Well yes, if you want to cast T& to X& and T and X are not related by
inheritance then you do need to use reinterpret_cast, but that should
make you think "maybe this is not a valid cast, maybe I shouldn't do
it" rather than "if I use reinterpret_cast the compiler doesn't
complain so it must be the way to go".